Knife grinder



FIG. 1 is perspective view thereof of a knife grinder showing my new design;

FIG. 2 a front elevational view;

FIG. 3 a rear elevational view thereof;

FIG. 4 a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines illustrate portions of the knife grinder which form no part of the claimed design. 

CLAIM The ornamental design for a knife grinder, as shown and described. 